Battle of Miyako Bay

What Happened

On 6 May 1869, a force of samurai loyal to the fallen Tokugawa shogunate attempted to seize the Kōtetsu (甲鉄), the ironclad flagship of the Imperial Japanese Navy, while it lay at anchor in Miyako Bay in northern Japan. The attackers belonged to the Republic of Ezo (蝦夷共和国, Ezo Kyōwakoku), a short-lived state that Tokugawa loyalists had proclaimed on the northern island of Hokkaidō after losing the main war on the mainland. Their plan was to board the Kōtetsu in a surprise night-and-dawn assault, kill its crew, and turn its guns against the Imperial fleet.

The operation failed. The attacking squadron approached under false foreign flags, but the defenders were alerted before the boarding parties could close, and the Kōtetsu's armour and firepower proved decisive. The loyalists withdrew with their ships damaged and their plan in ruins. The action lasted only a short time and formed one part of the wider Battle of Hakodate, the final campaign of the Boshin War.

Background

The Boshin War (戊辰戦争, Boshin Sensō) had begun in 1868 as a struggle between the Imperial court and its supporters on one side and the Tokugawa shogunate on the other. By the end of that year the shogunate had lost its capital, Edo, and its cause on the main island of Honshu. A hard core of Tokugawa loyalists refused to surrender. Under the leadership of Enomoto Takeaki (榎本武揚), an officer trained in the Netherlands and commander of the shogunate's navy, they sailed north with several warships and a body of troops.

In the winter of 1868–69 they occupied Hokkaidō and established the Republic of Ezo, the only republic in Japanese history before the modern era, with its capital at Hakodate. The new Meiji government, having consolidated power on the mainland, could not tolerate a rival state in the north. It assembled an expeditionary force and sent it to Hokkaidō.

The Kōtetsu was the centre of the loyalists' calculations. It was an ironclad ram, built abroad and recently acquired by the Meiji government, and it was the most powerful ship in Japanese waters. While the loyalist fleet still contained capable wooden warships, none could match an ironclad in a straight fight. If Enomoto's men could capture the Kōtetsu, the naval balance in the north would shift at once. The ship anchored in Miyako Bay, on the coast of what is now Iwate Prefecture, while escorting government transports northward, and the loyalists resolved to take it there.

Why It Mattered

The attack on the Kōtetsu was the boldest naval gamble of the Boshin War, and its failure sealed the fate of the Republic of Ezo. Had the boarding succeeded, the loyalists would have gained the strongest warship in the region and a realistic chance of contesting the sea around Hokkaidō. Instead they lost men, ships, and the element of surprise, and the Imperial fleet went on to support the landings and bombardments that reduced Hakodate.

The battle is also remembered as one of the earliest actions involving an ironclad warship in Japanese waters, and as a rare attempt at boarding and capture — a tactic from the age of sail — against a steam-powered, armour-plated opponent. It showed that industrial warship technology had already changed what was possible at sea, and that the Meiji government's investment in modern naval equipment had paid off at the decisive moment.

Within weeks of Miyako Bay, the fighting at Hakodate ended. Enomoto Takeaki surrendered in June 1869, and the Boshin War was over. The Meiji government's control of the whole archipelago was complete, and the era of the samurai as a military class moved rapidly toward its end.

The Name in Japanese

The Japanese name is 宮古湾海戦, read in kana as みやこわんかいせん and in romaji as Miyako-wan Kaisen.

• 宮 — read here as みや (miya). It means "palace" or "shrine". In place names it often carries the sense of a capital or a noble seat.
• 古 — read here as こ (ko). It means "old" or "ancient". Together, 宮古 (Miyako) is a place name: the city of Miyako and the bay beside it, on the Pacific coast of northern Honshu.
• 湾 — read here as わん (wan). It means "bay" or "gulf". This is the standard kanji for a bay in Japanese geography.
• 海 — read here as かい (kai). It means "sea" or "ocean".
• 戦 — read here as せん (sen). It means "war", "battle", or "combat".

So the whole name breaks down as Miyako (a place name) + bay + sea + battle: "the naval battle of Miyako Bay". The compound 海戦 (kaisen) is the ordinary Japanese word for a naval battle, and it appears in the names of many famous engagements. Note that 宮古 is written with the same characters as the city of Miyako in Iwate Prefecture, but it is a different place from Miyakojima in Okinawa, which uses the same first two kanji.

Key Figures

Enomoto Takeaki (榎本武揚) — the senior Tokugawa naval officer who led the loyalist fleet north and became president of the Republic of Ezo. The Miyako Bay operation was mounted under his overall authority as the loyalists' political and military leader.

**The crew of the Kōtetsu (甲鉄)** — the Imperial ironclad's officers and sailors, whose alertness and the ship's armour defeated the boarding attempt. The Kōtetsu was the target of the entire operation and the reason the loyalists sailed south from Hokkaidō.

The Tokugawa loyalist boarding force — the samurai and sailors of the Ezo squadron who attempted to take the Kōtetsu by surprise. Their failure at Miyako Bay left the Republic of Ezo without a path to control the sea, and the campaign at Hakodate ended in surrender within weeks.